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Biomedical subjects

M Osada

Publications and source records attributed to M Osada.

At least 91 records · Page 5Linked to original sources
PubMed1991

Protective effect of preconditioning on reperfusion induced ventricular arrhythmias of isolated rat hearts.

STUDY OBJECTIVE: The aim was to investigate the effect of preconditioning on reperfusion induced arrhythmias in the isolated working rat heart. DESIGN: Rat hearts were perfused with modified Krebs-Henseleit bicarbonate buffer. A 15 min period of global ischaemia was performed followed by a reperfusion period of 5 min. This procedure was repeated three times. Hearts were divided into the control group (n = 10) and the free radical scavenger group (n = 11). Hearts in the latter were reperfused in the presence of scavengers (SOD 3.5 x 10(4) U.litre-1 and catalase 5.0 x 10(5) U.litre-1). EXPERIMENTAL MATERIAL: Hearts were obtained from male Sprague-Dawley rats (270-350 g). MEASUREMENTS AND MAIN RESULTS: The incidence of reperfusion induced ventricular fibrillation in the control group decreased from 100% to 70% (NS) and to 40% (p less than 0.01) during the second and the third reperfusion periods, respectively. In the scavenger group, the incidence of ventricular fibrillation was the same in each reperfusion period at 45%. The time to onset of ventricular fibrillation increased at the second reperfusion in both groups. CONCLUSIONS: (1) The protective effect of preconditioning on reperfusion induced arrhythmia is evident in the isolated rat heart. (2) Addition of free radical scavengers reduced the incidence of reperfusion arrhythmia. However, the protective effect of preconditioning was lost.

Animals↗
PubMed1991

The role of oxygen free radicals and extracellular calcium ions in reperfusion-induced arrhythmias.

To examine the role of oxygen free radicals and extracellular calcium ions in reperfusion-induced ventricular arrhythmias, we evaluated the effects of hypoxic reperfusion, oxygen free radical scavengers, allopurinol and hypocalcemic reperfusion on reperfusion-induced ventricular arrhythmias. The hearts of male Sprague-Dawley rats were perfused in the working heart mode. Whole heart ischemia was induced for 15 min and then reperfused. Rats were divided into 5 groups: control group, scavenger group, allopurinol group, hypoxia group and hypocalcemia group. Scavenger, hypoxic and hypocalcemic perfusions were undertaken only during the period of perfusion. The incidence of reperfusion-induced ventricular fibrillation (Vf) was reduced in the scavenger group (100% to 38%) and the hypoxia group (100% to 50%). Spontaneous reversion of Vf to regular sinus rhythm was recognized in the hypoxia and hypocalcemia groups. In conclusion, oxygen free radicals would play an important role in the genesis of the reperfusion arrhythmias, and extracellular calcium concentration would also play an important role in sustaining the reperfusion arrhythmias. Notably, hypoxic reperfusion had protective effects on both processes.

Allopurinol↗
PubMed1990

The levels of prostaglandins associated with the reproductive cycle of the scallop, Patinopecten yessoensis.

The present experiment was undertaken to investigate the seasonal variations of levels of prostaglandins (PGs) and regulation of these levels in the ovary and hemolymph of the scallop. The levels of prostaglandin F2 alpha (PGF2 alpha) and prostaglandin E2 (PGE2) in the hemolymph and ovary increased during sexual maturation, and these levels in the ovary showed a marked increase in the spawning season. Consecutive administration of antiestrogen inhibited the increase of the levels of PGF2 alpha and PGE2 during sexual maturation. These results indicate that the seasonal variations of the levels of PGF2 alpha and PGE2 are closely related to the reproductive cycle, suggesting that PGF2 alpha and PGE2 may be involved in the sexual maturation and spawning of the scallop. Furthermore, it was supposed that estrogen likely plays a role in the regulation of PGs production in female, well known in mammals.

Animals↗
PubMed1989

[Development of laser systems in the treatment of hyperpigmented skin lesions].

Laser beams have been in common use for the treatment of hyperpigmented skin lesions. However, therapeutic efficacy has been limited mainly because the output is circular with a Gaussian distribution of intensity, which makes it difficult to apply a uniformly distributed dose to the lesions. We have developed a technique whereby a laser beam is converted to have a square and uniform output intensity distribution. The principle of this technique is that the divergent laser beam enters a glass square pillar, propagates through the pillar repeating the total reflection and emerges with a uniform intensity distribution over the cross-section at the end of the pillar. The device applied this technique is incorporated in a hand-piece and both ruby and argon laser systems have been developed. The ruby laser has been used for the treatment of the melanistic skin lesions such as nevus cell nevus and nevus spilus. In clinical application, 36 of 67 cases have shown remarkably effective results with an improvement rate of 53.7%. The argon laser has been used for the treatment of vasogenic skin lesions such as portwine stain. In clinical application, 44 of 66 cases have shown effective results and the improvement rate is 66.7%. These results are excellent when compared with the other methods of treatment and with laser therapy previously used.

Humans↗
PubMed1983

An electron microscopic study of solar ganglia in piglets infected with Aujeszky's disease virus.

Ten 2-day-old piglets were inoculated intranasally with Aujeszky's disease virus and their solar ganglia were examined by light and electron microscopy. The cytopathic change noticed was neuronal and glial cell degeneration. It was invariably associated with the virus replicated within the cells. All the main stages of virus development were observed in the degenerated ganglionic cells. Characteristically, plexiform vermicellar array and electron-dense tubular filaments were detected in a part of the nuclei of the infected neuron.

Animals↗
PubMed1983

Ultrastructural observation on the bacterial capsule of Bacillus anthracis seen in the spleen of a diseased cow.

The bacterial capsule of Bacillus anthracis seen in the spleen of a cow which had died of anthrax was studied electron microscopically. It was visible around bacteria which had been fixed in a ruthenium red-containing fixative. It was composed of electron-dense spikes and extended outwards from the bacterial surface. It was not found around bacteria which had been treated with a fixative devoid of ruthenium red. Bacteria were seen scattered among blood cells. They were not phagocytized by neutrophils or macrophages.

Animals↗
PubMed1982

Pathological studies on encephalitis in mice experimentally inoculated with bovine coronavirus.

One- to 21-day-old mice were examined pathologically after inoculated intracerebrally or subcutaneously with the Kakegawa strain of bovine coronavirus. In 1- to 4-day-old mice inoculated intracerebrally, the brain contained a small number of neutrophils and lymphocytes having infiltrated diffusely and perivascularly and some degenerative neurons. In mice inoculated intracerebrally at 7 to 21 days of age, severe necrosis of pyramidal cells was shown in Ammon's horn. Perivascular infiltrations of neutrophils and lymphocytes were moderate to severe. Some neurons were degenerative in the cerebral cortex, thalamus and midbrain. Degeneration of some neurons and mild infiltration of neutrophils and lymphocytes were observed in the brain of mice inoculated subcutaneously at 1 to 7 days of age. Perivascular infiltration of neutrophils and lymphocytes was prominent in the cerebral cortex of mice inoculated subcutaneously at 14 days of age. Cellular infiltration was also seen in the thalamus, Ammon's horn, midbrain, cerebellum and medulla oblongata. All the mice, except one, inoculated subcutaneously at 21 days of age were free from neural changes. Electron-microscopically, virus particles were observed in and outside of the degenerative neurons. They had a core 70 nm in diameter and an envelope with spikes.

Aging↗
PubMed1982

Morphology of sulfur granules produced by Staphylococcus aureus and Corynebacterium pyogenes in cows.

Sulfur granules produced by Staphylococcus aureus and Corynebacterium pyogenes were studied by light and electron microscopy. They consisted of bacteria and electron-dense amorphous substance which formed clubs in the periphery of each granule. In those produced by Staph. aureus, cocci were seen at the center of each granule. They were round or pleomorphic. Binary fission was frequently observed. In those produced by Coryn. pyogenes, degenerative bacteria were present at the center of each club. Bacteria found just beneath the club had a thick, electron-less-dense cell wall and electron-dense cytoplasm. Those present at the center of the granule were very long and had a cell wall thin and sometimes undulant, containing ribosomes. The electron-dense amorphous substance surrounded these bacteria and faced the neutrophils or epithelioid cells in the periphery of the granule both species of organisms. They might have been produced by bacteria. Cellular reactions of neutrophils, epithelioid cells, fibroblasts and plasma cells were seen around the sulfur granules produced by both species of organisms.

Animals↗
PubMed1981

Morphology of sulfur granules produced by Pseudomonas aeruginosa in cows.

A sulfur granule produced by Pseudomonas aeruginosa in three cows was studied light- and electron-microscopically. It consisted of clumps of basophilic bacteria and eosinophilic clubs. The clubs radiated from the periphery outward. The bacteria were stained dark red by both PAS and MacCallum-Goodpasture staining. Electron-microscopically, the sulfur granule consisted of electron-dense amorphous material and bacteria. The intact bacterium was about 0.45 micrometers in diameter and had an electron-dense cell wall 15 nm in width. Beneath the cell wall, moderately electron-dense fine granular material was present. The center of the bacterium was electron lucent. The club was electron-dense amorphous material. Degenerative bacteria and pilus-like structures were often seen in it. In one case, clusters of bacteriophages were present in and near the degenerative bacteria. Their head was hexagonal and 40 nm in diameter.

Animals↗
PubMed1981

A fiberscopic technique for the study of velopharyngeal closures (first report).

Velopharyngeal closures using a nasopharyngeal fiberscope and were recorded by a 16mm cine camera. The resting forms of the horizontal sections of velopharyngeal cavities were grouped into three types: the "oblate elliptical type", "prolate elliptical type" and "intermediate type". The manner and finished forms of closure were grouped into three types: the "soft palate type", "lateral wall type" and "mixed type". According to the definition, 11 out of 45 subjects studies showed the "soft palate type", eight showed the "lateral wall type" and the rest were classified as the "mixed type". There seemed to be some correlations between the closure forms and resting forms. Our method is thought to have two advantages with respect to the observation of various activities and halation-free observations.

Female↗
PubMed1981

Electron microscopy of cells cultured in serum-free medium after inoculation of swine vesicular disease virus.

Morphological alterations of IB-RS-2 cells cultured in serum-free maintenance medium after inoculation of swine vesicular disease virus (SVDV) were studied electron-microscopically. Cells harvested 0 to 3 hours after inoculation showed no alterations. Cellular alterations were observed from 4 to 7 hours after inoculation. Many vacuoles appeared just beneath the cytoplasmic membrane and were separated by thin cytoplasm. Narrow pathways were sometimes seen in the degenerative cells. They occasionally ran from the vacuole just beneath the cytoplasmic membrane to the nuclear cistern. Ribosome-like granules were seen along the narrow pathway or diffusely in the cytoplasm, or accumulated to form an islet. Membrane-bound bodies were frequently noticed in the central region of the cell. Cytoplasmic blebs were sometimes seen projecting from the cell surface. Vacuoles, narrow pathways and cytoplasmic blebs were absent in cells cultured in the medium with serum. So serum might exert some effects on the cytoplasmic membrane or cytoskeletal framework. Crystalline arrays of SVDV were found in the cytoplasm of degenerative cells harvested from 4 to 7 hours after inoculation. They were near the ribosome-like granules and membrane-bound bodies, but had no relationship with vacuoles just beneath the cytoplasmic membrane and narrow pathway. Their size and morphology were the same as those seen in the cells cultured in the medium with serum.

Animals↗
PubMed1980

Crystal formation of swine vesicular disease virus in porcine kidney cells (IB-RS-2 cells).

Crystal formation of swine vesicular disease virus (SVDV) in IB-RS-2 cells was studied by electron microscopy. Cells were harvested 0, 3, 3.5, 4, 4.5, 5, 6 and 7 hours after inoculation. Crystalline arrays of SVDV was first observed in the cytoplasm of a few cells 4.5 hours after inoculation. In the cytoplasm of many cells harvested at 5 hours, 1 to 3 crystalline arrays of SVDV were observed. After that, a small number of cells had crystalline arrays in the cytoplasm. The cells with crystalline arrays were rich in ribosome and polysome with dilated mitochondria and many tiny vesicles. An individual virus particle was ca. 18 nm in diameter, and the center-to-center space ca. 22 nm. Crystalline arrays varied in size depending on the plane of section.

Animals↗
PubMed1980

A histological and ultrastructural comparison of the sulfur granule of the actinomycosis and actinobacillosis.

The sulfur granules of actinomycosis and actinobacillosis were studied histologically and ultrastructurally. The sulfur granule of actinomycosis was large, and oval or horsehoe-shaped. In it, there were a number of gram-positive, filamentous or short rod-like hyphae beneath clubs. Ultrastructurally, the center of the sulfur granule was composed of a cluster of hyphae, and the periphery was surrounded by clubs arranged radially. The clubs were made of electron-dense fine granules and had a degenerated hypha at the center. These granules varied in amount from small to large. As for the host reaction, neutrophil infiltration appeared first around the sulfur granule. Then epithelioid cells proliferated and phagocytized hyphae. Finally, proliferating fibroblasts enclosed them and formed tiny granulomas. The sulfur granule of actinobacillosis was small and lobulated. In it, a number of gram-negative, short rod-like bacteria were present beneath clubs. Ultrastructurally, the center of the sulfur granule contained intact or degenerated bacteria, and the periphery was composed of radially projecting clubs. These clubs were made of electron-dense amorphous material, in which several layers of tubular structures surrounded the bacterium conentrically. The host reaction was almost the same as that of actinomycosis. The proliferation of fibroblasts was prominent. There was a strong tendency for these cells to form many tiny granulomas.

Actinobacillosis↗